it depends

It depends on how good you are with the computer.

If I were you, I will try to start the system to safe mode. (press F8 when system start) Then save all the important files like documents, photos or songs etc.

Next I will try to get into the command mode and copy
the boot files like:

COPY C:\i386\NTLDR C:
COPY C:\i386\NTDETECT.COM C:

Then, I will try to recover the system by command "bootfix".

The last resort is to re-install XP from scratch.
1) go to the BIOS and set first boot from CD
2) put CD and follow the instructions

good luck